Structural studies on banana oil, isoamyl acetate, by means of microwave spectroscopy and quantum chemical calculations

Abstract

The rotational spectrum of isoamyl acetate, H₃C–COO–(CH₂)₂–CH(CH₃)₂, has been recorded and assigned using a molecular beam Fourier transform microwave (MB-FTMW) spectrometer in the frequency range of 3–26.5 GHz. One conformer has been observed. By comparing the spectroscopic data with the quantum chemical data, it was found that the conformer observed does not have C_s symmetry. The rotational and centrifugal distortion constants were determined. The barrier to internal rotation of the acetate methyl group was found to be 93.98 cm⁻¹. Due to the high number of the conformers, a systematic nomenclature will be presented.

Keywords:

• banana oil
• isoamyl acetate
• internal rotation
• quantum chemistry calculation
• microwave spectroscopy

Acknowledgements

We would like to thank Claudia Wessel and Sonja Winterle for numerous measurements on isoamyl acetate during their student research project. We further thank the computer centre of the RWTH Aachen University for computer time and the state of Nordrhein-Westfalen for funds. The authors also want to thank the PHC PROCOPE for travel grants.